1. Field of the Invention
The present invention relates to a method and a computer program for operating a forced-induction internal combustion engine.
2. Description of Related Art
The compression of a fuel/air mixture in a combustion chamber (cylinder) of an internal combustion engine relevant here can be modified in essence by varying the point in time at which intake valves disposed on the cylinders close. The point in time at which an intake valve closes, indicated with reference to the so-called “bottom dead center point” in the context of combustion, is modified, for example in the context of a variable valve train, by way of a phase-shiftable intake camshaft.
A method for operating an internal combustion engine with a variable compression ratio is evident from published German patent application document DE 102 58 872 A1. With the method therein, starting of the internal combustion engine is accomplished at a compression ratio that is decreased with respect to compression ratios during normal operation of the internal combustion engine. FIG. 1 therein describes an apparatus for generating a variable compression ratio, but in this case the technical details regarding implementation of a variable compression ratio are not of importance.
It is furthermore known to optimize the compression ratio in two different directions when designing internal combustion engines. The “compression ratio” refers to the volume of the entire cylinder space prior to compression, in relation to the remaining volume once compression has occurred. In naturally aspirated engines the compression ratio is designed for high combustion efficiency, whereas with forced-induction engines the principal concern is the least possible mechanical stress on those components of the internal combustion engine which are involved in combustion and in forced induction, and thus optimal protection from possible mechanical overload.